Taiwan-developed app finds smartphone use impact on sleep, health

Taipei, April 1 (CNA) Taiwan researchers have devised an app called "Rhythm," which shows that the use of smartphones before bed has a great impact on sleep by delaying circadian rhythms, reducing sleep times and as a result, jeopardizing health.

Utilizing a questionnaire and the Rhythm app to record the smartphone behavior of 61 people aged 20-56 over 14 days, a research team from Taiwan's National Health Research Institutes (NHRI) discovered that one hour of increased smartphone use per day delays circadian rhythm by 3.5 minutes and decreases total sleep time by 5.5 minutes.

Often referred to as the "body clock," the circadian rhythm is a 24-hour cycle that tells the body when to sleep, rise and eat -- regulating many physiological processes.

"Smartphone use before bedtime was only around 14.3 percent of total use, but had around 44 percent of the impact on sleep," the NHRI said in a statement Monday, citing the research results from the team led by Lin Yu-hsuan (林煜軒), an assistant investigator and attending physician at the NHRI's Institute of Population Health Sciences.

While previous literature shows that light exposure impacts circadian rhythms, Lin's research team demonstrated that the use of smartphones before bed significantly affects the body's clock, the NHRI said.

At Monday's press conference, Lin said a mere several minute delay of bedtime might look like nothing, but in many clinical cases, he has seen sleep-troubled patients who could suffer anxiety only because they went to bed five minutes later than usual.

Such patients would begin to worry about work and daily life trifles while in bed and as a result, they fall asleep later but still have to get up early for work or school.

"The delay of circadian rhythm poses a threat to life tempo and health," warned Lin.

He was referring to the impact of the direct and strong smartphone light on the function of the pineal gland and the secretion of melatonin, a serotonin-derived hormone that modulates sleep patterns in both circadian and seasonal cycles.

There has been much research that confirms that disruption of circadian rhythm can cause diseases ranging from mental illness, metabolic disease, cardiovascular disease, diabetes, high blood pressure and strokes, to a variety of cancers, such as breast and prostate cancer, Lin said.

The research results have been published in the March 2019 issue of the Journal of Psychiatric Research.

The "Rhythm" app -- a smartphone-based automatic sleep recording system developed by Lin's team -- enables academia and clinicians to engage in long-term naturalistic and objective recording of daily sleep patterns over months or years, for studies focused on the risk that irregular sleep patterns might cause to psychiatric and medical health, according to the NHRI.

The method in which the "Rhythm" app collects data of sleep times and smartphone use is based on the times of the screen turning on and off, the NHRI statement said.

Most importantly, Lin's team is the first to propose "proactive use" (turning on the smartphone, making phonecalls, using apps) and "reactive use" (receiving calls, receiving notifications) in their analytical algorithm to predict sleep times and precisely calculate the impact of smartphone use on sleep times.

"Statistical analysis shows that our methodology has 84 percent correlation to the results of the user questionnaire," the NHRI said.

Lin said the "Rhythm" app is completely automatic and collects data continuously to calculate sleep times, and is also power efficient.

Unlike similar products currently on the market, which require users to manually set, wear or place the device properly in order to monitor and record behavior, the new app can precisely calculate smartphone use and its impact on sleep, giving more objective data than a user's self-reporting or questionnaire, according to Lin.

The "Rhythm" app is considered to be a breakthrough in research methodology and will have great potential in the fields of sleep medicine and psychiatry, the NHRI said.